6. The voice of Admiral Ackbar
Apparently he has quite a following, although he was never put in the movie credits.

"Erik Bauersfeld, 90 years old, performed the voices of Admiral Ackbar and Bib Fortuna in "Return of the Jedi." He's still never seen the original "Star Wars," and the recording was a very small job in his respected broadcasting career. But he has developed a nice relationship with fans of the series, returning their letters and refusing to charge money for autographs."(via Neatorama)